Electrolysis.



' bine With thecalcium forming, in the first CLARENCE A. HALL, OF MOUNT AIRY, PENNSYLVANIA.

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Specification of Letters Patent. I Patented Dec. 14}, 19 115. 7

Ho Drawing. Application filed March 6, 1913, Serial No. 752,378. Renewed September 8, 1915. Serial No. 49,612. Y

To all whom it may concern:

Be it known that I, CLARENCE A. HALL, a citizen of the United States, residing at Mount Airy, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Electrolysis, of which the following is a specification.

The principal object of the present invention is to maintain the free ion concentration, of anelectrolyte favorable for the disposition of ions during electrolysis. According to my invention this objectis accomplished by the presence in the electrolyte of a compound insoluble in the electrolyte, and which with the ions set free by electrolysis forms a passive compound.

For the sake of a further description of the invention it will be described in connection with the electrolytic recovery of zinc from a zinc sulfate solution or a zinc chlorid solution. In either case there is added to the .solution finely divided calcium carbonate. During electrolysis the calcium carbonate-is decomposed by the liberated ions which cominstance, calcium sulfate, which is sparingly soluble, and,-in the second instance, calcium chlorid, which is soluble. These calcium compounds are electrically inert in this electrolyte. During electrolysis commercial metallic zinc is deposited as distinguished from mossy zinc, such as results from electrolysis as heretofore attempted. The proportion of calcium compound added should be sufiicient to take up the liberated ions or slightly in excess. My process does not require any marked departure from ordinary practice concerning current density and the like, nor are diaphragms necessary. Since the added compound is insoluble in the electrolyte, it i is obvious that it should not be allowed to settle, and one Way of preventing this is to keep the electrolyte agitated as by stir-- ring it.

While the invention is principally applicable to the electrolytic deposition of 'zinc,

because commercial zinc is recovered, still the invention is not necessarily confined to that use.

What I claim as new and desire to secure by Letters Patent is: V

1. The process of maintaining the free anion concentration of an electrolyte constant during electrolysis which consists in carrying on electrolysis in the presence of a solid finely divided substance which is in- Soluble in the absence of the current and which in the presence of the current combines With the liberated anions, forming a compound electrically inert in the electrolyte,'and continually and thoroughly agitatlyte during electrolysis.

2. The process of maintaining the free anion concentration of a zinc electrolyte coning the finely divided substance and electrocarrying on electrolysis in the presence of a finely divided substance which is insoluble in the absence of the current'and which in the presence of the current combines with the liberated anions, forming a compound electrically inert in the electrolyte, and continually and thoroughly agitating the finely divided substance and electrolyte during electrolysis.

In testimony whereof I have hereunto signed my name.

I CLARENCE A. HALL. Witnesses:

CLIFFORD K. CASSEL,

FRANK E. FRENCH. 

